Portable biosensor for air sample

ABSTRACT

Provided is a portable biosensor that includes a sample filter cartridge, a filter collector, an optical sphere, an electromagnetic radiation emitter, a photo-detector, a processor, a signal display, a vacuum pump, and a power supply. The sample filter cartridge selectively removes small molecules to minimize spectral interference in the detection signal. The sample is concentrated onto the filter collector and subjected to illumination by the electromagnetic radiation emitter, producing Raman-scattering. The optical sphere collects and distributes the Raman-scattering shifts, which then pass through a spectral filter to produce spectral filtered scattering, which is then reflected by the concave holographic flat-field grating onto the photo-detector. The data is displayed graphically to provide the Raman-scattering shift data. The data is compared with a database for sample identification. The device is contained within a housing that is small enough to be easily transported for field use.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 63/321,398, filed Mar. 18, 2022, entitled “PORTABLEVIRUS SENSOR IN AIR,” the disclosure of which is expressly incorporatedby reference herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The invention described herein was made in the performance of officialduties by employees of the Department of the Navy and may bemanufactured, used and licensed by or for the United States Governmentfor any governmental purpose without payment of any royalties thereon.This invention (Navy Case 210986US02) is assigned to the United StatesGovernment and is available for licensing for commercial purposes.Licensing and technical inquiries may be directed to the TechnologyTransfer Office, Naval Surface Warfare Center Corona Division, email:CRNA_CTO@navy.mil.

FIELD OF THE INVENTION

The field of invention relates generally to air sensors. Moreparticularly, it pertains to a portable biosensor for air sample.

BACKGROUND

Rapid, reliable, accurate, and early detection for biological proteinsamples, such as viral particles is always in constant demand globally.The COVID-19 outbreak revealed inadequate technologies in meeting thisdemand, as accurate PCR assays require at least 24 hours for results,making quick clinical decisions impractical. Alternative means fortesting include chemical instruments, including those based onspectroscopy, electrochemistry, and microscopy. As an example,spectroscopy based methods include light-scattering spectrometry,absorption spectrometry, fluorescence spectrometry, mass spectrometry,and Raman scattering spectrometry. One limitation with thesespectrometric instruments are they are generally lab-based. Whileportable devices have been developed and are commercially available,these portable units are used on liquid and/or solid samples.

Among these spectrometers, ones based on Raman Scattering are the mostpopular. Raman excitation generates Raman Scattering shifts (peaks) to awavelength region with high fluorescence signal. Raman ScatteringSpectrometry is capable of finger-print identification of a substance ofinterest, however, this technique usually generates a weak signal fordetection. Another technique, Light Scattering Spectrometry, has shownpotential for viral detection, as it provides particle-size information.This technique, however, provides no chemical information. A combinationof these two spectrometric techniques appears promising for viralparticle detection, however, current hardware devices that are known andutilized in the art are too bulky and complicated to be packaged into asmall portable/hand-held unit. As is evident from the above, a portablebiosensor that combines Raman Scattering Spectrometry and for detectingviral particles in an air sample is desirable.

SUMMARY OF THE INVENTION

The present invention relates to a portable biosensor comprising: asample filter cartridge; a first air passage; a filter collector; anoptical sphere; an electromagnetic radiation emitter; a photo-detectorconfigured to receive electromagnetic spectrum data; a processor inelectrical communication with the photo-detector to receive theelectromagnetic spectrum data from the photo-detector; a signal displayin electrical communication with the processor and configured to providean indication of the electromagnetic spectrum data; a second airpassage; a vacuum pump for drawing an air sample from the sample filtercartridge, through the first air passage, the filter collector, theoptical collector, and the second air passage and out the vacuum pump;and a power supply in electrical communication with the electromagneticradiation emitter, the photo-detector, the processor, the signaldisplay, and the vacuum pump.

The sample filter cartridge selectively removes small molecules such aswater, ammonia, and carbon dioxide in order to minimize spectralinterference in the detection signal. The sample is collected andconcentrated onto the filter collector and subjected to illumination bythe electromagnetic radiation emitter, producing intense scattering. Theoptical sphere collects and uniformly distributes the Raman-scatteringshifts at a wall of the optical sphere, causing the Raman-scatteringshifts to exit the optical sphere and to pass through a spectral filter,which produces spectral filtered scattering. The spectral filteredscattering is collected, separated, and reflected by the concaveholographic flat-field grating onto the photo-detector, which is thenconverted into electrical signals and is displayed graphically by thesignal display to provide an indication of the electromagnetic spectrumdata comprising the Raman-scattering shift data. The data is comparedwith a database for sample identification. The device is containedwithin a housing that is small enough to be easily transported for fielduse (approximately the size of a small shoe-box).

Additional features and advantages of the present invention will becomeapparent to those skilled in the art upon consideration of the followingdetailed description of the illustrative embodiment exemplifying thebest mode of carrying out the invention as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings particularly refers to theaccompanying figures in which:

FIG. 1 shows the portable virus sensor.

FIG. 2 shows a close-up view of the sample filter cartridge.

FIG. 3 shows a view of the filter collector, optical sphere, andelectromagnetic radiation emitter.

FIG. 4 shows a close-up view of the optical sphere, the photo-detector,and the concave holographic flat-field grating.

FIG. 5 shows a close-up view of the processor, signal display, and powersupply.

FIG. 6 shows a close-up view of the second air passage and vacuum pump.

DETAILED DESCRIPTION OF THE DRAWINGS

The embodiments of the invention described herein are not intended to beexhaustive or to limit the invention to precise forms disclosed. Rather,the embodiments selected for description have been chosen to enable oneskilled in the art to practice the invention.

Generally, provided is a portable biosensor comprising: a sample filtercartridge; a first air passage; a filter collector; an optical sphere;an electromagnetic radiation emitter; a photo-detector configured toreceive electromagnetic spectrum data; a processor in electricalcommunication with the photo-detector to receive the electromagneticspectrum data from the photo-detector; a signal display in electricalcommunication with the processor and configured to provide an indicationof the electromagnetic spectrum data; a second air passage; a vacuumpump for drawing an air sample from the sample filter cartridge, throughthe first air passage, the filter collector, the optical collector, andthe second air passage and out the vacuum pump; a power supply inelectrical communication with the electromagnetic radiation emitter, thephoto-detector, the processor, the signal display, and the vacuum pump;and a housing that is sized for portability of said biosensor for fielduse.

In an illustrative embodiment, the sample filter cartridge furthercomprises a 30 μm pore size mesh filter, a 1.0 μm pore size coarsefilter, a 0.5 μm pore size medium filter, 0.5 μm pore size fine filter,and a molecular-sieve bead-column. In an illustrative embodiment, theelectromagnetic radiation emitter further comprises a Ramen spectrometerlaser diode. In an illustrative embodiment, the spectrometer laser diodeemits a deep ultra-violet radiation wavelength of 180 nm to 250 nm at asample collected on the filter collector. In an illustrative embodiment,the sample collected on the filter collector absorbs the radiation andgenerates Raman-scattering shifts comprising finger-print spectral peaksthat are about 30 nm longer than the emitted radiation in afluorescence-free spectral region. In an illustrative embodiment, theoptical sphere collects and uniformly distributes the Raman-scatteringshifts at a wall of the optical sphere, causes the Raman-scatteringshifts to exit the optical sphere and to pass through a spectral filterselected from the group consisting of a notch filter, a band-passfilter, and a long-pass spectral filter to produce spectral filteredscattering, wherein the spectral filter blocks scattering radiationproduced by the electromagnetic radiation emitter. In an illustrativeembodiment, the spectral filtered scattering is collected, separated,and reflected by a concave holographic flat-field grating onto thephoto-detector. In an illustrative embodiment, the spectral filteredscattering data is collected from the photo-detector and is displayedgraphically by the signal display to provide an indication of theelectromagnetic spectrum data comprising the Raman-scattering shiftdata. In an illustrative embodiment, the Raman-scattering shift data iscompared with a database for sample identification.

The biosensor provides an effective, low-cost, small size, low weight,simple, easy to use device with point-of-care/remote operation foraccurate and rapid sample detection/testing. In an illustrativeembodiment, the sample is a human breath sample. In an illustrativeembodiment, the human breath sample is tested for viral particles. In anillustrative embodiment, the viral particles are COVID-19 viralparticles. In an illustrative embodiment, testing is done directly onthe virus sample without the need for time-consuming polymerase chainreaction (PCR) processes.

FIG. 1 shows the portable biosensor 100. In an illustrative embodiment,the device comprises a sample filter cartridge 101; a first air passage102; a filter collector 103; an optical sphere 104; an electromagneticradiation emitter 105; a photo-detector 106; a processor 107; a signaldisplay 108; a second air passage 109; a vacuum pump 110; and a powersupply 111. In an illustrative embodiment, the portable biosensor 100 iscontained within a housing 112 that is sized for portability and forfield use In an illustrative embodiment, the biosensor is containedwithin a housing 112 approximately the size of a small shoe-box.

FIG. 2 shows a close-up view of the sample filter cartridge 101. In anillustrative embodiment, the sample filter cartridge 101 selectivelyremoves small molecules such as water (resulting in dry-particles foraccurate sizing), ammonia, and, carbon dioxide (for minimizing andavoiding spectral interference in the detection signal), and detectparticles in the 50-150 nm size-range by providing a spectral samplefinger-print for comparison to samples in a database. The removal ofsmall molecules is achieved with one or more filters contained in thesample filter cartridge 101.

In an illustrative embodiment, is constructed of plastic and furthercomprises a 30 μm pore size mesh filter 201, a 1.0 μm pore size coarsefilter 202, a 0.5 μm pore size medium filter 203, and a molecular-sievebead-column 204. The sampling-air will be vacuum-drawn into thecartridge 101 and through the mesh filter 201 for preventing entrance oflarger particles, the bead-column 204 for removing small chemicalmolecules, coarse filter 202 and medium filter 203 for removing largeand medium sized particles, respectively, and finally through the finefilter for collecting and concentrating small (50-150 nm) particles. Inan illustrative embodiment, one or more of the filters are disposable.The sample filter cartridge 101 allows air to flow therethrough and isattached to the first air passage 205 in a secure manner. In anillustrative embodiment, the bead-column 204 contains synthetic crystalswith small pores. The size of the pores determines what size moleculescan enter and be trapped. As a non-limiting example, a pore diameter of˜3 angstroms (A) will trap molecules of that size or smaller; andtherefore molecules of water, ammonia, and carbon dioxide will betrapped and removed from the air stream. In an illustrative embodiment,beads (˜10 mesh) can be packed as a column segment in the cartridge 101.

FIG. 3 shows a view of the filter collector 103, optical sphere 104, andelectromagnetic radiation emitter 105. In an illustrative embodiment,the filter collector 103 is a 0.5 μm pore size fine filter. In anillustrative embodiment, electromagnetic radiation passes through anoptical port 301 of several mm in diameter, and is directed and focusedonto the filter collector 103, where Raman excitation on particles takesplace. The sample will be collected and concentrated onto the filtercollector 103 and subjected to illumination by the electromagneticradiation emitter 105, producing intense scattering. The amount ofsample particles concentrated onto the filter collector 103 is directlyproportional to the length of collection time.

In an illustrative embodiment, the filter collector 103 comprises aceramic-filter embedded with nanoparticles of gold, silver, copper,semiconductor quantum dots, and/or graphene oxide. In an illustrativeembodiment, the filter collector 103 comprises a metal filter such assilver filter. The small dimension will maximize particle-concentratingand sample-exposure to the illumination beam, and the nanoparticles orsilver surface will greatly enhance the intensity of Raman scattering.In an illustrative embodiment, the filter collector 103 can beconstructed of aluminum oxide, polycarbonate, or silver. In anillustrative embodiment, a silver filter can be used directly withoutsurface modification.

In an illustrative embodiment, the electromagnetic radiation emitter 105further comprises a Ramen spectrometer laser diode. In an illustrativeembodiment, the Ramen spectrometer laser diode employs a laser diode orexcimer lamp for providing a deep ultra-violet (UV) radiation within therange of 180-250 nm wavelength. The sample on the filter collector 103absorbs radiation and generates Raman-Scattering shifts as finger-printspectral peaks, within ˜30 nm longer than the source radiation to afluorescence-free spectral region for detection, with the characteristicpeaks appearing in the range of about 350-3800 cm−1.

Raman Scattering Spectrometry (Layman Theory) is a technique thatutilizes a high intensity illumination source (in the present case, aRamen spectrometer laser diode) to strike and “shake” a sample ofinterest, causing the sample release “peaks”. The peaks are spectrally(in term of wavelength or wave number) shifted away from the shakinglight (wavelength). Identification of these peaks leads to a“fingerprint spectrum” for the substance of interest. The inventivedevice utilizes a laser diode of deep-UV wavelength that is resonantlyabsorbed by protein sample, which in turn generates high peaks fordetection. The additional benefit for the deep-UV shifted peaks is thatthey appear in a fluorescence free spectral region.

As can be appreciated, a common Raman shift problem is that the peaksoverlap in high fluorescence region, causing peak identificationdifficult. The inventive biosensor overcomes this problem by generatingRaman-Scattering shifts in a fluorescence-free region, which results ina high signal-to-background ratio for improved detection. The opticalsphere 104 is closed when the air-inlet 302 is open for samplecollection, and is closed to prevent ambient light-entrance andlaser-exposure during detection.

Additionally, the Raman effect is strongly enhanced by several orders ofmagnitude if the sample substrate contains a shiny, reflective,nano-metal-particles (silver, gold, copper), which is known as SurfaceEnhance Raman Scattering. This enhancement is caused by more effectiveenergy dissipation on the sample of interest via a partially metal“plasmonic” effect. In an illustrative embodiment, the sample isembedded with nano-particles, including metals, crystals ofsemi-conductor materials, and organics, such as graphene and grapheneoxides. In an alternate embodiment, metal-filters a silver-filter can beutilized.

The optical sphere 104 collects and uniformly distributes theRaman-scattering shifts at a wall 303 of the optical sphere 104, causingthe Raman-scattering shifts to exit the optical sphere 104 and to passthrough a spectral filter 304 selected from the group consisting of anotch filter, a band-pass filter, and a long-pass spectral filter. Thespectral filter 304 produces spectral filtered scattering, wherein thespectral filter 304 blocks scattering radiation produced by theelectromagnetic radiation emitter 105. The spectral filter 304 blocksthe source (laser/lamp) scattered radiation (which generates highbackground) but passes Raman Scattering radiation (detects as signal),at the optical slit 305. A key consideration for selecting a suitablespectral-filter is that the Raman Scattering “peaks” in general, willshift several nanometer to about 30 nanometer longer than the sourceradiation wavelength employed.

FIG. 4 shows a close-up view of the optical sphere 104, thephoto-detector 106, and the concave holographic flat-field grating 401.The grating component separates the radiation. while the concave-mirrorcomponent 402 reflects and focuses the separated “color-images” onto thephoto-detector 106. The multiple-function capability of the concaveholographic flat-field grating 401 reduces the number of opticalcomponents, allowing for the construction of a compact device and thereduction of scattered light, in turn providing a high signal-to-noisesignal for detection.

In an illustrative embodiment, the spectral filtered scattering iscollected, separated, and reflected by the concave holographicflat-field grating 401 onto the photo-detector 106. In an illustrativeembodiment, the photo-detector 106 is a tall charge-coupled devicedetector (CCD) array. In an illustrative embodiment, the CCD heightmatches the image height of the spectral filtered scattering, allowingfor optimal detection.

The CCD senses the spectrum of light-ray dispersed by the grating 401,converts the spectrum into electrical signals, and outputs the result.In an illustrative embodiment, the CCD is constructed with an array ofpixel sensing-elements. In an illustrative embodiment, the pixel size isbetween 10-30 In an illustrative embodiment, a cooled CCD can beutilized to reduce background noise. In an illustrative embodiment, anuncooled CCD is used for enhanced portability.

FIG. 5 shows a close-up view of the processor 107, signal display 108,and power supply 111. In an illustrative embodiment, the spectralfiltered scattering data is collected from the CCD and is displayedgraphically by the signal display 108 to provide an indication of theelectromagnetic spectrum data comprising the Raman-scattering shiftdata. The power supply 111 is in electrical communication with theelectromagnetic radiation emitter, the photo-detector, the processor107, the signal display 108, and the vacuum pump. In an illustrativeembodiment, the power supply 111 is a battery. In an illustrativeembodiment, the power supply 111 is utilizes alternating current throughan electrical outlet.

FIG. 6 shows a close-up view of the second air passage 109 and vacuumpump 110. In an illustrative embodiment, the vacuum pump 110 draws anair sample from the sample filter cartridge, through the first airpassage, the filter collector, the optical collector, and the second airpassage and out the vacuum pump.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe spirit and scope of the invention as described and defined in thefollowing claims.

1. A portable biosensor comprising: a sample filter cartridge; a firstair passage; a filter collector; an optical sphere; an electromagneticradiation emitter; a photo-detector configured to receiveelectromagnetic spectrum data; a processor in electrical communicationwith said photo-detector to receive said electromagnetic spectrum datafrom said photo-detector; a signal display in electrical communicationwith said processor and configured to provide an indication of saidelectromagnetic spectrum data; a second air passage; a vacuum pump fordrawing an air sample from said sample filter cartridge, through saidfirst air passage, said filter collector, said optical collector, andsaid second air passage and out said vacuum pump; a power supply inelectrical communication with said electromagnetic radiation emitter,said photo-detector, said processor, said signal display, and saidvacuum pump; and a housing that is sized for portability of saidbiosensor for field use.
 2. The biosensor of claim 1, wherein saidsample filter cartridge further comprises a 30 μm pore size mesh filter,a 1.0 μm pore size coarse filter, a 0.5 μm pore size medium filter, anda molecular-sieve bead-column.
 3. The biosensor of claim 1, wherein saidelectromagnetic radiation emitter further comprises a Ramen spectrometerlaser diode.
 4. The biosensor of claim 3, wherein said Ramenspectrometer laser diode emits a deep ultra-violet radiation wavelengthof 180 nm to 250 nm at a sample collected on said filter collector. 5.The biosensor of claim 4, wherein said sample collected on said filtercollector absorbs said radiation and generates Raman-scattering shiftscomprising finger-print spectral peaks that are about 30 nm longer thansaid emitted radiation in a fluorescence-free spectral region.
 6. Thebiosensor of claim 5, wherein said optical sphere collects and uniformlydistributes said Raman-scattering shifts at a wall of said opticalsphere, causes said Raman-scattering shifts to exit said optical sphereand to pass through a spectral filter selected from the group consistingof a notch filter, a band-pass filter, and a long-pass spectral filterto produce spectral filtered scattering, wherein said spectral filterblocks scattering radiation produced by said electromagnetic radiationemitter.
 7. The biosensor of claim 6, wherein said spectral filteredscattering is collected, separated, and reflected by a concaveholographic flat-field grating onto said photo-detector.
 8. Thebiosensor of claim 7, wherein said spectral filtered scattering data iscollected from said photo-detector and is displayed graphically by saidsignal display to provide an indication of said electromagnetic spectrumdata comprising said Raman-scattering shift data.
 9. The biosensor ofclaim 8, wherein said Raman-scattering shift data is compared with adatabase for sample identification.
 10. A portable biosensor comprising:a sample filter cartridge; a filter collector; an optical sphere; aRamen spectrometer laser diode, a photo-detector configured to receiveelectromagnetic spectrum data; a processor in electrical communicationwith said photo-detector to receive said electromagnetic spectrum datafrom said photo-detector; a signal display in electrical communicationwith said processor and configured to provide an indication of saidelectromagnetic spectrum data; a vacuum pump; a power supply.
 11. Thebiosensor of claim 10, wherein said sample filter cartridge furthercomprises a 30 μm pore size mesh filter, a 1.0 μm pore size coarsefilter, a 0.5 μm pore size medium filter, and a molecular-sievebead-column.
 12. The biosensor of claim 11, wherein said Ramenspectrometer laser diode emits a deep ultra-violet radiation wavelengthof 180 nm to 250 nm at a sample collected on said filter collector. 13.The biosensor of claim 12 wherein said sample collected on said filtercollector absorbs said radiation and generates Raman-scattering shiftscomprising finger-print spectral peaks that are about 30 nm longer thansaid emitted radiation in a fluorescence-free spectral region.
 14. Thebiosensor of claim 13, wherein said optical sphere collects anduniformly distributes said Raman-scattering shifts at a wall of saidoptical sphere, causes said Raman-scattering shifts to exit said opticalsphere and to pass through a spectral filter selected from the groupconsisting of a notch filter, a band-pass filter, and a long-passspectral filter to produce spectral filtered scattering, wherein saidspectral filter blocks scattering radiation produced by saidelectromagnetic radiation emitter.
 15. The biosensor of claim 14,wherein said spectral filtered scattering is collected, separated, andreflected by a concave holographic flat-field grating onto saidphoto-detector.
 16. The biosensor of claim 15, wherein said spectralfiltered scattering data is collected from said photo-detector and isdisplayed graphically by said signal display to provide an indication ofsaid electromagnetic spectrum data comprising said Raman-scatteringshift data.
 17. The biosensor of claim 16, wherein said Raman-scatteringshift data is compared with a database for sample identification.
 18. Aportable biosensor comprising: a sample filter cartridge; a first airpassage; a filter collector; an optical sphere; an electromagneticradiation emitter; a photo-detector configured to receiveelectromagnetic spectrum data; a processor in electrical communicationwith said photo-detector to receive said electromagnetic spectrum datafrom said photo-detector; a signal display in electrical communicationwith said processor and configured to provide an indication of saidelectromagnetic spectrum data; a second air passage; a vacuum pump fordrawing an air sample from said sample filter cartridge, through saidfirst air passage, said filter collector, said optical collector, andsaid second air passage and out said vacuum pump; a power supply inelectrical communication with said electromagnetic radiation emitter,said photo-detector, said processor, said signal display, and saidvacuum pump; and a housing that is sized for portability of saidbiosensor for field use; wherein said electromagnetic radiation emitterfurther comprises a Ramen spectrometer laser diode that emits a deepultra-violet radiation wavelength of 180 nm to 250 nm at a samplecollected on said filter collector; wherein said sample collected onsaid filter collector absorbs said radiation and generatesRaman-scattering shifts comprising finger-print spectral peaks that areabout 30 nm longer than said emitted radiation in a fluorescence-freespectral region; wherein said optical sphere collects and uniformlydistributes said Raman-scattering shifts at a wall of said opticalsphere, causes said Raman-scattering shifts to exit said optical sphereand to pass through a spectral filter selected from the group consistingof a notch filter, a band-pass filter, and a long-pass spectral filterto produce spectral filtered scattering, wherein said spectral filterblocks scattering radiation produced by said electromagnetic radiationemitter; wherein said spectral filtered scattering is collected,separated, and reflected by a concave holographic flat-field gratingonto said photo-detector; wherein said spectral filtered scattering datais collected from said photo-detector and is displayed graphically bysaid signal display to provide an indication of said electromagneticspectrum data comprising said Raman-scattering shift data; and whereinsaid Raman-scattering shift data is compared with a database for sampleidentification.